MOSCOW, July 22 (Reuters) - President Vladimir Putin said on Tuesday Russia would use its influence with separatists in east Ukraine to allow a full investigation into the downing of a Malaysian airliner, but said the West must put pressure on Kiev to end hostilities.

Putin also called on Western powers not to meddle in Russia's domestic affairs and said steps were needed to strengthen the country's military capabilities because of moves by NATO and to protect the economy from "external threats".

"We are being called on to use our influence with the separatists in southeastern Ukraine. We of course will do everything in our power but that is not nearly enough," Putin said at the start of a meeting with defence and security chiefs.

"Ultimately, there is a need to call on the authorities in Kiev to respect basic norms of decency, and at least for a short time implement a ceasefire," he said.

Putin's comments were his first detailed response in public to Western criticism of Russia's role in Ukraine since the Malaysian airliner was brought down on Thursday, killing 298 people.

Reading from notes at the head of a long table with officials seated on each side, Putin spoke much more forcefully than during brief televised remarks on the plane's downing first released in the early hours of Monday, when he had seemed less assured than usual.

Putin reiterated his belief that protests that toppled Ukraine's former Russian-backed leader were instigated and funded from abroad.

Despite Western sanctions, he said Moscow would stand by separatists in eastern Ukraine whom, he described as part of a popular rising against an illegal coup.

"Russia is being presented with what is almost an ultimatum: 'Let us destroy this part of the population that is ethnically and historically close to Russia and we will not impose sanctions against you," Putin said. "This is a strange and unacceptable logic."

He did not, however, directly address the question of whether Russia has been arming the rebels - he has denied such accusations before. (Reporting by Daria Korsunskaya; Writing by Alissa de Carbonnel, Editing by Timothy Heritage)